For any student who wants to read mathematics at undergraduate level should purchase this book. It is an introduction to mathematical proof and at its present price of approximately £8 is a good buy. I think you can download it free from the authors’ personal webpage.
It has a large number of exercises to reinforce your understanding and some good illustrations.
I do not know who published this book but it lacks a polished output and gives the impression that it has been printed on a local printer and bounded together; maybe this is why it can be sold at such a cheap price. Additionally it only gives solutions to odd numbered questions which can be off putting to a student who wants to use this book for self-learning.